1. Field of the Invention
The present invention relates to a measuring endoscope apparatus and, more particularly, to a measuring endoscope apparatus in which a plurality of optical adaptors can be replaced to use at the tip of an insertion portion of the endoscope.
2. Description of the Related Art
In general, the detailed examination of a subject by using an endoscope requires the measuring of the position of the subject. To satisfy this request, conventionally, various measuring apparatuses using the endoscope are proposed.
For example, a proposal disclosed in Japanese Unexamined Patent Application Publication No. 10-248806 shows a measuring endoscope apparatus for stereo measuring.
Further, a proposal disclosed in Japanese Patent Application No. 2000-101122 by the applicant of the present invention shows a measuring endoscope apparatus which automatically selects and executes measuring methods varied depending on the type of optical adaptor.
In the measuring endoscope apparatus disclosed in the former Japanese Unexamined Patent Application Publication No. 10-248806, an optical adaptor having two optical systems necessary for capturing the image of a subject for measuring is detachably arranged in a main body of an endoscope. Two images through two lens systems in the optical adaptor are formed on one image pick-up device and at least the obtained image through the endoscope is subjected to the image processing, thus performing the measuring of the subject. The measuring endoscope apparatus comprises measuring means which executes processing for reading information from a recording medium on which optical data of the optical adaptor is recorded, processing for correcting the optical data based on a position error of an image pick-up system of the main body of the endoscope, processing for a coordinate transformation of a measuring targeted image based on the corrected optical data, and processing for obtaining three-dimensional coordinates at an arbitrary point by matching two images based on the two coordinate-transformed images.
In the measuring endoscope apparatus having the above-mentioned structure, the three-dimensional coordinates are obtained at the arbitrary point of the subject by matching the two images based on two pieces of image information which are obtained by a coordinate transformation of two images of the subject, that is, captured by the image pick-up device via the optical adaptor. Consequently, the measuring endoscope apparatus can be realized with low price and excellent measuring precision.
The above-mentioned measuring endoscope apparatus is a measuring endoscope apparatus which mainly performs stereo measuring. In addition, the measuring endoscope apparatus can execute comparison and measurement by attaching a detachable normal optical adaptor having a single optical system to the tip of the same endoscope and using an image obtained by the normal optical adaptor.
On the other hand, as disclosed in the latter Japanese Patent Application No. 2000-101122, there are provided the measuring endoscope apparatus comprising a connecting portion provided at the tip of the endoscope, a plurality of types of optical adaptor detachable to the connecting portion, for forming a subject image on an image pick-up device, which performs the measurement by connecting one type of optical adaptor and by performing image processing for an image signal obtained by the image pick-up device, wherein measuring endoscope apparatus further comprises menu display means that performs menu display processing for selecting operation based on display data previously associated with the plurality of optical adaptors and performs measurement based on the selected result in the menu display processing.
In those conventional measuring endoscope apparatuses, the optical adaptor is selected on the menu, thereby a measuring method corresponding to the selected optical adaptor is automatically selected. The measuring can be executed corresponding to the selected measuring method only by pressing a measuring executing switch provided for an endoscope operating portion, in the case of executing the measurement.
In an embodiment disclosed in Japanese Patent Application No. 2000-101122, images of the plurality of optical adaptors are subjected to calibration. The resultant images are stored in a memory card of compact flash (trade mark) as an external storage medium, as data on a measurement environment. In the disclosed structure, by selecting the optical adaptor used on the menu, the data on the measurement environment is selected and used corresponding to the selected optical adaptor.
In the above-disclosed technologies, the measurement based on a stereo image needs processing (calibration) in which a positional relationship between the image pick-up device and the plurality of optical systems provided for the image pick-up device is accurately grasped in advance and the difference of the positional relationship is corrected. However, when attaching the optical adaptor, in an optical-adaptor-replacing-type stereo endoscope, the position varies depending on the attachment of the optical adaptor when hitching the optical adaptor to the tip of the endoscope and, in accordance therewith, the positional relationship between the image pick-up device and the optical system of the optical adaptor might vary. In this case, the difference between the positional relationship between the image pick-up device and the optical system to which the optical adaptor is attached and the previously-performed calibration result might cause the decrease in measuring precision. In order to prevent the decrease in measuring precision, there is a method in which the calibration is performed every time the optical adaptor is attached. However, the calibration on every attachment of the optical adaptor requires complicated processing sequence. A processing capacity of microprocessors used for the current measuring endoscope takes a long time for the calibration.
Further, when a plurality of optical adaptors are provided and the measurement is performed by exchanging the optical adaptors, the measurement can easily be performed by storing the calibration result which is executed for every optical adaptor, as the data on the measurement environment, and switching the data on the measurement environment when exchanging the optical adaptor. However, the measurement might be implemented in a state in which the optical adaptor mismatches the data on the measurement environment stored as the calibration result because only the optical adaptor is replaced and the data on the measurement environment is not selected. This might decrease the measuring precision.